1. Field of Invention
The present invention relates to a fuel tank assembly and method of securing a component in a fuel tank using induction welding.
2. Background of Related Art
To save time and money and improve reliability, manufacturers have been switching from metal fuel tanks to thermoplastic fuel tanks. Thermoplastic fuel tanks generally have lower material cost, lower manufacturing costs, increased longevity, and are not subject to corrosion. One problem with thermoplastic fuel tanks is that vapors may permeate through the fuel tanks walls. To address this permeation problem and in view of stricter emissions requirements, manufacturers have added permeation resistant layers to fuel tanks and have attempted to form fuel tanks out of as few pieces as possible.
While permeation resistant layers and blow molded fuel tanks reduce permeation, problems still arise when components, such as fill tubes, vent tubes, roll over valves, and vent valves, are attached to the fuel tank. During attachment many manufacturers drill holes through the wall of the fuel tank and weld the component to the outside of the fuel tank. However, each opening breaches the permeation resistant layer creating permeation pathways.
As an alternative to creating separate holes for each component, some manufacturers have attempted to move the attached components inside the container using a single access hole. In this approach, the component is secured to an interior surface readily accessible from the access hole by directly welding the component to the fuel tank using hot plate welding. In hot plate welding, a plate disposed between the component and fuel tank is heated, typically through resistive heating, until the component is capable of being bonded to the fuel tank and the plate is displaced so that the component may be placed into contact with the fuel tank to form a bond area as the component and fuel tank cool. While this approach reduces the number of potential permeation pathways, the components generally are located approximately opposite the opening within the fuel tank wall in a limited bonding area. The limited bonding area typically includes a pump and fuel level sensor assembly held by spring loaded rods against the bottom of the fuel tank. Attempts to offset the component from the limited bonding area have resulted in prolonged manufacturing cycle times due to the delay in cooling the heating elements used to weld the component to the tank wall before removal from the fuel tank. Further, commonly used heating elements (such as hot plates) have significant mass requiring excessive time to heat and cool the heating element.
In view of the above, a need exists for an apparatus and method having faster cycle times for welding components to an inner surface of a fuel tank and, preferably, for an apparatus and method that permits the component to be secured to a tank surface offset from the access opening.